fopen, fscanf, nested for loops

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Tiffany McGinnis 2019-3-8

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https://ww2.mathworks.cn/matlabcentral/answers/448922-fopen-fscanf-nested-for-loops

评论： Image Analyst 2019-3-8

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Check the file ID to determine if the file is available.

Only print message if file is not available.

Use nested for loops to read one water level value at a time into the lake_powell matrix.

lake_powell(month,year) = fscanf(fileID, '%f', 1);.

Use mean to determine the average elevation of the water level for each year and the overall average for the four-year period over which the data were collected. Print the yearly average vector and the overall average with labels as shown below.

%*****CONSTANT*****
 
fileID= fopen('lake_powell.txt');
lake_powell = fscanf(fileID, '%f', 1);
 
if exist('lake_powell.txt', 'file')
  % File exists.  Do stuff....
 
%*****INPUT*****
% read data file
years = ( 2013:1:2016 );
fprintf('\nLake Powell Water Levels (in feet)\n');
 
% if file doesn't exist
 
if exist('lake_powell.txt', 'file')
  % File exists.  Do stuff....
  
 
% print title and year column headings.
for i=1:length(years)
    fprintf('%6.0d\t', years(i));
end
% print contents of lake_powell
for i=1:size(lake_powell,1)
    fprintf('\n')
    for j=1:size(lake_powell,2)
        fprintf('%.2f\t',lake_powell(i,j));
    end 
end
fprintf('\n');
 
% PART B: use mean to determine average elevation 
fprintf('\n');
mean_each_year = mean(lake_powell,1);
fprintf('\n     Average for Each Year (in feet)\n');
 for i=1:length(years)
    fprintf('%9.0d',years(i)); 
fprintf('\n'); 
for i=1:length(mean_each_year)
    fprintf('%10.2f',mean_each_year(i));
end
end 
 overall_mean= mean(mean_each_year);
fprintf('\n   Overall average:%10.2f feet',overall_mean);
 else
    disp('File not found');
end 
 
 else
    disp('File not found');
end 